/* -------------------------------------------------------------------------
 * help_config.c
 *
 * Displays available options under grand unified configuration scheme
 *
 * Options whose flag bits are set to GUC_NO_SHOW_ALL, GUC_NOT_IN_SAMPLE,
 * or GUC_DISALLOW_IN_FILE are not displayed, unless the user specifically
 * requests that variable by name
 *
 * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *	  src/backend/utils/misc/help_config.c
 *
 * -------------------------------------------------------------------------
 */
#include "postgres.h"
#include "knl/knl_variable.h"

#include <float.h>
#include <limits.h>

#include "utils/guc_tables.h"
#include "utils/help_config.h"
#include "utils/memutils.h"
#include "utils/plog.h"

/*
 * This union allows us to mix the numerous different types of structs
 * that we are organizing.
 */
typedef union {
    struct config_generic generic;
    struct config_bool cbool;
    struct config_real real;
    struct config_int integer;
    struct config_string string;
    struct config_enum _enum;
} mixedStruct;

static void printMixedStruct(mixedStruct* structToPrint);
static bool displayStruct(mixedStruct* structToDisplay);

int GucInfoMain(void)
{
    struct config_generic** guc_vars;
    int numOpts, i;

    MemoryContextInit();

    /* Initialize the guc_variables[] array */
    build_guc_variables();

    guc_vars = get_guc_variables();
    numOpts = GetNumConfigOptions();

    for (i = 0; i < numOpts; i++) {
        mixedStruct* var = (mixedStruct*)guc_vars[i];

        if (displayStruct(var))
            printMixedStruct(var);
    }

    return 0;
}

/*
 * This function will return true if the struct passed to it
 * should be displayed to the user.
 */
static bool displayStruct(mixedStruct* structToDisplay)
{
    return !(
        (unsigned int)structToDisplay->generic.flags & (GUC_NO_SHOW_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE));
}

/*
 * This function prints out the generic struct passed to it. It will print out
 * a different format, depending on what the user wants to see.
 */
static void printMixedStruct(mixedStruct* structToPrint)
{
    printf("%s\t%s\t%s\t",
        structToPrint->generic.name,
        GucContext_Names[structToPrint->generic.context],
        _(config_group_names[structToPrint->generic.group]));

    switch (structToPrint->generic.vartype) {

        case PGC_BOOL:
            printf("BOOLEAN\t%s\t\t\t", (structToPrint->cbool.reset_val == 0) ? "FALSE" : "TRUE");
            break;

        case PGC_INT:
            printf("INTEGER\t%d\t%d\t%d\t",
                structToPrint->integer.reset_val,
                structToPrint->integer.min,
                structToPrint->integer.max);
            break;

        case PGC_REAL:
            printf(
                "REAL\t%g\t%g\t%g\t", structToPrint->real.reset_val, structToPrint->real.min, structToPrint->real.max);
            break;

        case PGC_STRING:
            printf("STRING\t%s\t\t\t", structToPrint->string.boot_val ? structToPrint->string.boot_val : "");
            break;

        case PGC_ENUM:
            printf("ENUM\t%s\t\t\t", config_enum_lookup_by_value(&structToPrint->_enum, structToPrint->_enum.boot_val));
            break;

        default:
            write_stderr("internal error: unrecognized run-time parameter type\n");
            break;
    }

    printf("%s\t%s\n",
        (structToPrint->generic.short_desc == NULL) ? "" : _(structToPrint->generic.short_desc),
        (structToPrint->generic.long_desc == NULL) ? "" : _(structToPrint->generic.long_desc));
}
